Serial interfaces (was Re: Any former Psion 5 owners out there?)

25 Jul 2010

...
   that a USB
device can't present itself as a port on 0x378 on IRQ 7
 etc.  
 Well, wasn't it actually 0x3bc on the original PC?  And I don't see why  
Sort-of. The parallel port on the MDA card (and on most clone monochrome 
cards with printer ports) was at 0x3bc. The port on the printer card was 
at 0x378, and there was a jumper to move it to 0x278.

The IBM ROM BIOS (at leas in the PC, XT, and AT machines) looked for 
printer ports at 0x3bc, 0x378 and 0x278 in that order. The first one it 
found became LPT1:, tjhe second one LPT2:, and so on. 

-tony

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Serial interfaces (was Re: Any former Psion 5 owners out there?)